Multi-zone formation fluid evaluation system and method for use of same

ABSTRACT

A formation fluid evaluation system ( 100 ) interconnected within a tubular string ( 118 ) for operation in a wellbore ( 102 ) having multiple zones ( 106, 108, 110 ). The evaluation system ( 100 ) includes a pair of straddle packers ( 120, 122 ) that isolates one zone ( 108 ) of the multiple zones ( 106, 108, 110 ), a test valve ( 124 ) disposed between the straddle packers ( 120, 122 ) and an upper packer ( 126 ) positioned uphole of the uppermost zone ( 106 ) of the multiple zones ( 106, 108, 110 ). A fluid lift assembly ( 128 ) is position uphole of the upper packer ( 126 ). The fluid lift assembly ( 128 ) is operable to draw fluid ( 134 ) from the isolated zone ( 108 ) into the tubular string ( 118 ) through the test valve ( 124 ). A formation evaluation instrument ( 136 ) is disposed within the tubular string ( 118 ) and determines a characteristic of the fluid ( 134 ) received from the isolated zone ( 108 ).

TECHNICAL FIELD OF THE INVENTION

The present invention relates, in general, to testing and evaluation of subterranean formation fluids and, in particular, to a single trip, multi-zone formation fluid evaluation system and method for unloading fluids from each zone prior to evaluating reservoir fluids at reservoir conditions.

BACKGROUND OF THE INVENTION

Without limiting the scope of the present invention, its background is described with reference to testing hydrocarbon formations, as an example.

It is well known in the subterranean well drilling and completion art to perform tests on formations intersected by a wellbore. Such tests are typically performed in order to determine geological or other physical properties of the formations and the fluids contained therein. For example, parameters such as permeability, porosity, fluid resistivity, temperature, pressure and bubble point may be determined. These and other characteristics of the formations and fluids contained therein may be determined by performing tests before the well is completed.

One type of testing procedure that is commonly performed is to obtain a fluid sample from each formation or zone to, among other things, determine the composition of the formation fluids in that zone. In this procedure, it is important to obtain a sample of the formation fluids that is representative of the fluids as they exist in the reservoir. In a typical sampling procedure, a sample of the formation fluids may be obtained by lowering a sampling tool having a sampling chamber into the wellbore on a conveyance such as a wireline, slick line, coiled tubing, jointed tubing or the like. When the sampling tool reaches the desired depth, one or more ports are opened to allow collection of the formation fluids. Once the ports are opened, formation fluids travel through the ports and a sample of the formation fluids is collected within the sampling chamber of the sampling tool. After each sample is collected, the sampling tool is withdrawn from the wellbore so that the formation fluid sample may be analyzed. Typically, this procedure must be repeated for each zone of interest that is intersected by the wellbore. Accordingly, use of such sampling techniques can be quite time consuming in wellbores have multiple zones.

In addition, it has been found that fluid loss into certain formations occurs during the drilling and cementing phases of well construction. In such wells, before a representative fluid sample at reservoir conditions can be obtained, the fluid lost into the formation must be unloaded or swabbed to initiate the flow of reservoir fluids into the wellbore. This swabbing process may take hours for each zone causing days of delay in wells having multiple zones.

Therefore, a need has arisen for an apparatus and method for evaluating reservoir fluids from multiple zones in a single trip. A need has also arisen for such an apparatus and method that reduce the time spent unloading fluid lost into the formations during the drilling and cementing phases of well construction.

SUMMARY OF THE INVENTION

The present invention disclosed herein provides a system and method for evaluating reservoir fluids from multiple zones in a single trip. In addition, the system and method of the present invention reduce the time spent unloading fluid lost into the formations during the drilling and cementing phases of well construction.

In one aspect, the present invention is directed to a formation fluid evaluation system that is interconnected within a tubular string for operation in a wellbore having multiple zones. The evaluation system utilizes a pair of straddle packers that isolates one zone of the multiple zones. A test valve is disposed between the straddle packers. The test valve receives fluid from the isolated zone into the interior of the tubular string. An upper packer is positioned uphole of an uppermost zone of the multiple zones. A fluid unloading assembly is position uphole of the upper packer. The fluid unloading assembly is operable to draw fluid from the isolated zone into the tubular string through the test valve. A formation evaluation instrument is disposed within the tubular string. The formation evaluation instrument is used to determine a characteristic of the fluid received from the isolated zone. The formation fluid evaluation system is operable to sequentially isolate individual zones of the multiple zones and evaluate fluid received from the individual zones in a single trip.

In one embodiment of the test valve, a screen element is used to filter fluids entering the tubular string from the isolated zone. In one embodiment of the fluid unloading assembly, a pump is used to unload the fluids. For example, the pump may be a jet pump, a progressive cavity pump, a hydraulic pump, an electrical submersible pump, a syringe pump or the like. In another embodiment of the fluid unloading assembly, a gas lift valve is used to allow nitrogen or other lift gas to lighten the fluid from the isolated zone.

In one embodiment of the formation evaluation instrument, a conveyance is used to lower the formation evaluation instrument into the tubular string and through the fluid unloading assembly. In another embodiment of the formation evaluation instrument, at least one sensor is coupled to the tubular string. In yet another embodiment, data obtained by the formation evaluation instrument relative to the characteristic of the fluid is transmitted to the surface via a conductor operably associated with the formation evaluation instrument. In a further embodiment, data obtained by the formation evaluation instrument relative to the characteristic of the fluid is transmitted to the surface via a wireless telemetry device operably associated with the formation evaluation instrument. In any of these embodiments, the characteristic of the fluid may be at least one of temperature, pressure, flow rate and fluid composition.

In one embodiment of the formation fluid evaluation system, a treatment valve may be disposed between the straddle packers. The treatment valve is operable to inject a treatment fluid from the tubular string into the isolated zone.

In another aspect, the present invention is directed to a method of evaluating multiple zones during a single trip into a wellbore. The method includes interconnecting a formation fluid evaluation assembly within a tubular string, disposing the formation fluid evaluation assembly in the wellbore proximate one zone of the multiple zones and isolating the zone, providing a seal uphole of an uppermost zone of the multiple zones, unloading fluid from the isolated zone into the tubular string, receiving reservoir fluid from the isolated zone into the interior of the tubular string, determining a characteristic of the reservoir fluid received from the isolated zone and performing the disposing, isolating, providing, unloading, receiving and determining steps for each of the multiple zones in a single trip.

In certain implementations, the method may involve filtering the fluid entering the tubular string from the isolated zone, pumping the fluid from the isolated zone to the surface, lifting the fluid from the isolated zone to the surface or obtained data relative to the characteristic of the fluid and transmitting the data to the surface via a conductor or via wireless telemetry.

In a further aspect, the present invention is directed to a method of evaluating multiple zones during a single trip into a wellbore. The method includes interconnecting a formation fluid evaluation assembly within a tubular string, disposing the formation fluid evaluation assembly in the wellbore proximate one zone of the multiple zones and isolating the zone, providing a seal uphole of an uppermost zone of the multiple zones, unloading fluid from the isolated zone into the tubular string, receiving reservoir fluid from the isolated zone into the interior of the tubular string, determining a characteristic of the reservoir fluid received from the isolated zone, if the characteristic of the reservoir fluid received from the isolated zone matches a predetermined characteristic, then treating the isolated zone and repeating the receiving and determining steps. The method also includes performing the disposing, isolating, providing, unloading, receiving, determining and conditional treating steps for each of the multiple zones in a single trip.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, including its features and advantages, reference is now made to the detailed description of the invention, taken in conjunction with the accompanying drawings in which like numerals identify like parts and in which:

FIG. 1 is a schematic illustration of one embodiment of a formation fluid evaluation system embodying principles of the present invention;

FIG. 2 is a schematic illustration of another embodiment of a formation fluid evaluation system embodying principles of the present invention;

FIG. 3 is a schematic illustration of a further embodiment of a formation fluid evaluation system embodying principles of the present invention;

FIG. 4 is a schematic illustration of yet another embodiment of a formation fluid evaluation system embodying principles of the present invention;

FIGS. 5A-5B are schematic illustrations of one embodiment of a formation fluid evaluation system embodying principles of the present invention;

FIGS. 6A-6B are schematic illustrations of another embodiment of a formation fluid evaluation system embodying principles of the present invention; and

FIGS. 7A-7B are schematic illustrations of a further embodiment of a formation fluid evaluation system embodying principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the invention.

Referring initially to FIG. 1, therein is representatively illustrated a formation fluid evaluation system that is generally designated 100 and which embodies principles of the present invention. Formation fluid evaluation system 100 is disposed within a wellbore 102 that includes casing 104. Wellbore 102 traverses various earth strata including a plurality of zones of interest such as zones 106, 108, 110 which may be portions of a common formation or reservoir, or one or more of the zones may be portions of separate formations or reservoirs. As illustrated, casing 104 includes perforation 112, 114, 116 that correspond in location with zones 106, 108, 110, respectively.

Although three zones 106, 108, 110 are depicted in FIG. 1, any number of zones may be tested with formation fluid evaluation system 100. In fact, one important feature of the present invention is that all of the zones of interest including zones 106, 108, 110 can be conveniently and relatively quickly tested in a single trip of formation fluid evaluation system 100 into wellbore 102. It should be noted that the term “single trip” is well known to those skilled in the art, and as used herein, the term indicates an operation commencing with an initial insertion of formation fluid evaluation system 100 into wellbore 102 and ending with a next subsequent complete retrieval of formation fluid evaluation system 100 from wellbore 102.

Formation fluid evaluation system 100 is interconnected within a tubular string 118 that is preferably made from a plurality of joints of pipe threadably coupled together to form the string. Alternatively, however, tubular string 118 could be formed from other types of tubing including coiled tubing or segmented tubing coupled together by other means. At its lower end, formation fluid evaluation system 100 includes isolation packer 120 and isolation packer 122 that operate as a pair of straddle packers to isolate the zone of interest to be tested. Packers 120, 122 may be similar in design or may vary in setting and releasing technique. For example, packer 122 may be a rotation set packer while packer 120 may be a compression set and release packer. In the illustrated embodiment, packers 120, 122 each include a pair of seal elements that provide a seal against the interior surface of casing 104. Packers 120, 122 are designed such that the integrity of the seals created between the packer elements and casing 104 can be tested prior to operation of formation fluid evaluation system 100. For example, a pressure reading may be taken between the packer elements by opening a sliding sleeve of packers 120, 122 to determine if any leaks exist.

Disposed between packers 120, 122 is a test valve 124. Test valve 124 is used to selectively allow and prevent fluids from entering the interior of tubing string 104 from the exterior of tubing string 104. More specifically, during operation of formation fluid evaluation system 100, test valve 124 is used to selectively allow and prevent fluids from entering the interior of tubing string 104 from the zone being tested, zone 108 in the illustrated embodiment. Test valve 124 may be a sliding sleeve valve or other suitable fluid flow control device. Test valve 124 may also provide a choking functionality to control production into tubing string 104.

Formation fluid evaluation system 100 includes an upper packer 126 that may have the same or a different design than either packers 120, 122 and may preferably be a compression set and release packer. In operation, upper packer 126 is positioned uphole of the uppermost zone of the multiple zones traversed by wellbore 102. In the illustrated example, the uppermost zone is depicted as zone 106. As explained in greater detail below, positioning packer 126 uphole of the uppermost zone prevent any power fluid or gas lift fluid, in those embodiments using such fluid, from entering zones above the isolated zone during operation of formation fluid evaluation system 100.

Formation fluid evaluation system 100 also includes a fluid unloading assembly 128. As illustrated, fluid unloading assembly 128 may be positioned uphole of upper packer 126. Fluid unloading assembly 128 may be a pump, such as a fluid operated pump including turbine pumps, hydraulic driven piston pumps or jet pumps, or may be a valve, such as a gas lift valve, used to aid in removal of fluid from tubular string 104. Specifically, in operation, fluid unloading assembly 128 is used to draw fluid from the isolated zone, illustrated as zone 108, into tubular string 104 through test valve 124 and move this fluid to the surface.

In the illustrated embodiment, fluid unloading assembly 128 is being operated by a power fluid 130, depicted as arrows with hollow arrowheads, that is circulated down the tubing-casing annulus 132. Power fluid 130 then enters fluid unloading assembly 128 and passes upwardly through a nozzle that is configured to increase a velocity of power fluid 130, thereby creating a region of reduced pressure about the nozzle exit. As such, fluid unloading assembly 128 operates as a jet pump to carry fluids from zone 108 to the surface in a mixture consisting of power fluid 130 and fluid from the zone being tested, which is depicted as arrows 134 having solid arrowheads. The mixture is then circulated through the tubular string 118 to the surface. It should be noted, however, that various other flow paths may be used in other configurations of fluid unloading assembly 128, such circulating the power fluid down the tubular string and the mixture of power fluid and fluid from the zone up the tubing-casing annulus 132 without departing from the principles of the present invention.

In the illustrated embodiment, fluid unloading assembly 128 also includes a passageway that allows certain tools, such as a formation evaluation instrument 136, to pass therethrough and receives other tools securably and sealing therein. Specifically, fluid unloading assembly 128 includes a nipple of the type which includes an internal landing profile and a seal bore for securing and sealing tools, such as a plug (not pictured), therein. In this configuration, the plug is received within fluid unloading assembly 128 to provide a seal that prevents fluid from passing through the seal bore and forces fluid 134 to pass through the jet pump section. This configuration is achieved using a pair of Y-blocks on the upper and lower ends of fluid unloading assembly 128 that provides the two fluid paths through fluid unloading assembly 128.

As illustrated, a formation evaluation instrument 136 has passed through fluid unloading assembly 128. Formation evaluation instrument 136 is deployed within tubular string 104 on a conveyance 138 that extends from the surface. Conveyance 138 may be a wireline, a slick line, an electric line, a coiled tubing or the like. In operation, formation evaluation instrument 136 is positioned adjacent or above perforations 114 and includes a plurality of sensors for determination of one or more characteristics of the fluid. For example, formation evaluation instrument 136 may include sensors for pressure, temperature, flow rate, density, fluid identification, resistivity, capacitance and water cut or any other type of sensor or combination of sensors desired. In addition, formation evaluation instrument 136 may include a flow control device, such as a valve or choke, and one or more sampling chambers for obtaining fluid samples.

If formation evaluation instrument 136 is in the form of a conventional wireline or slickline conveyed production logging tool, formation evaluation instrument 136 may be retrieved from the well at any time, without also retrieving the remainder of formation fluid evaluation system 100. In this configuration, formation evaluation instrument 136 could include one or more memory modules which record data for download at the surface and may be reinstalled as many times as desired to acquire sufficient data for evaluation of each of the zones of interest. Alternatively, formation evaluation instrument 136 could be conveyed on a conductor cable that provides powered and control signals to formation evaluation instrument 136 such that real time data from formation evaluation instrument 136 can be sent to the surface.

The characteristics of fluid 134, including changes in the characteristics over time, changes in the characteristics in response to induced stimulus and the like are used to evaluate the properties of the zone, its associated formation or reservoir, the fluid therein and the like. These evaluations or any portion of them may be performed in formation evaluation instrument 136 itself or in a computerized system at the surface. In this case, the computerized system may supply power, receive records and processes data, communicate command and control signals, and otherwise facilitates the testing and evaluation of the zones using formation evaluation instrument 136. While such a computerized system is preferably positioned at a surface location, the computerized system or any portion of it could alternatively be located elsewhere and communication thereto could be provided via satellite transmission, Internet transmission or the like.

In operation, formation fluid evaluation system 100 is operable to sequentially isolate individual zones 106, 108, 110 of the multiple zones traversed by wellbore 102 and evaluate fluid received from the individual zones 106, 108, 110 in a single trip. To achieve this result tubular string 118 is installed in wellbore 102 such that straddle packers 120, 122 isolate a portion of annulus 132 adjacent each of the zones 106, 108, 110 when each respective zone is being tested. As depicted in FIG. 1, annulus 132 above and below zone 108 is sealed off by the packers 120, 122 straddling perforations 114 formed through casing string 104. Preferably, formation fluid evaluation system 100 is used to evaluate the lowermost zone, depicted as zone 110, first then progresses uphole, zone by zone, until all zones of interest are tested. Accordingly, FIG. 1 depicts a scenario in which the fluids from zone 110 have previously been tested, the fluids from zone 108 are current being tested and the fluids from zone 106 are yet to be tested.

Once packers 120, 122 are set and zone 108 is isolated, the integrity of the seal created between packers 120, 122 and casing string 104 may be tested. If it is determined that the seal is good, packer 126 may then be set above the uppermost zone 106. If not already deployed, formation evaluation instrument 136 is now run downhole on conveyance 138 to a location at or near perforations 114 within tubular string 118. Conveyance 138 also deploys a plug that seals within fluid unloading assembly 128 to prevent flow through the seal bore of fluid unloading assembly 128 during pumping. Fluid communication between the interior of tubular string 118 and zone 108 via perforations 114 can then be established by operating test valve 124 to an open position. As zone 108 may have taken on fluids during the drilling and cementing phases of well construction, fluid unloading assembly 128 is used to unloading this fluid until reservoir fluids are produced from zone 108. This is achieved, in the illustrated embodiment, by circulating power fluid 130 through fluid unloading assembly 128 to carry fluids 134 from zone 108 to the surface via tubular string 118. After some or all of the fluid being produced from zone 108 is reservoir fluid, formation evaluation instrument 136 is used to determine one or more characteristics of the reservoir fluid, such as the presence of oil in the fluid. This determination can be made by formation evaluation instrument 136 downhole or data relating to the evaluated characteristics may be sent to the surface via a conductor cable associated with conveyance 138 or by retrieving formation evaluation instrument 136 to the surface.

Due to the unique configuration of formation fluid evaluation system 100, each of the multiple zones 106, 108, 110 can be evaluated in this manner by merely repositioning formation fluid evaluation system 100 in wellbore 102 adjacent a respective one of the zones and isolating that zone, providing a seal uphole of the uppermost zone, unloading fluid from the isolated zone, receiving reservoir fluid from the isolated zone into the interior of the tubular string and determining a characteristic of the reservoir fluid received from the isolated zone.

Even though FIG. 1 depicts a vertical well, it should be noted by one skilled in the art that the formation fluid evaluation system of the present invention is equally well-suited for use in deviated wells, inclined wells or horizontal wells. As such, the use of directional terms such as above, below, upper, lower, upward, downward and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure. Also, even though FIG. 1 depicts a cased wellbore, it should be understood by those skilled in the art that the formation fluid evaluation system of the present invention is equally well-suited for use in an open hole environment using, for example, inflatable packers.

Referring next to FIG. 2, therein is representatively illustrated a formation fluid evaluation system that is generally designated 200 and which embodies principles of the present invention. Formation fluid evaluation system 200 is disposed within a wellbore 202 that includes casing 204. Wellbore 202 traverses various earth strata including a plurality of zones of interest such as zones 206, 208, 210. As illustrated, casing 204 includes perforation 212, 214, 216 that correspond in location with zones 206, 208, 210, respectively.

Formation fluid evaluation system 200 is interconnected within a tubular string 218. At its lower end, formation fluid evaluation system 200 includes isolation packer 220 and isolation packer 222 that operate as a pair of straddle packers to isolate the zone of interest to be tested. Disposed between packers 220, 222 is a test valve 224 that is used to selectively allow and prevent fluids from entering the interior of tubular string 204 from the exterior of tubular string 204. In the illustrated embodiment, test valve 224 includes a screen element that filters any solids of a predetermined size out of fluids entering test valve 224.

Formation fluid evaluation system 200 includes an upper packer 226 positioned uphole of the uppermost zone 206. Positioned uphole of upper packer 226 is fluid unloading assembly 228 that is depicted as a fluid operated pump wherein power fluid 230 circulated through annulus 232 drives fluid unloading assembly 228 such that fluid 234 from isolated zone 208 is drawn into tubular string 204 through test valve 224 and up to the surface. Fluid unloading assembly 228 also includes a nipple and a seal bore that allow the passage of formation evaluation instrument 236 carried by conveyance 238 therethrough and is sealed by a plug also carried by conveyance 238. In this configuration, fluid 234 can be pumped uphole to unload zone 208 until reservoir fluid is produced. The characteristics of the fluid produced from zone 208 can then be evaluated by formation evaluation instrument 236 or other systems associate with formation evaluation instrument 236.

Due to the unique configuration of formation fluid evaluation system 200, each of the multiple zones 206, 208, 210 can be evaluated in this manner by merely repositioning formation fluid evaluation system 200 in wellbore 202 adjacent a respective one of the zones and isolating that zone, providing a seal uphole of the uppermost zone, unloading fluid from the isolated zone, receiving reservoir fluid from the isolated zone into the interior of the tubular string and determining a characteristic of the reservoir fluid received from the isolated zone.

Referring next to FIG. 3, therein is representatively illustrated a formation fluid evaluation system that is generally designated 300 and which embodies principles of the present invention. Formation fluid evaluation system 300 is disposed within a wellbore 302 that includes casing 304. Wellbore 302 traverses various earth strata including a plurality of zones of interest such as zones 306, 308, 310. As illustrated, casing 304 includes perforation 312, 314, 316 that correspond in location with zones 306, 308, 310, respectively.

Formation fluid evaluation system 300 is interconnected within a tubular string 318. At its lower end, formation fluid evaluation system 300 includes isolation packer 320 and isolation packer 322 that operate as a pair of straddle packers to isolate the zone of interest to be tested. Disposed between packers 320, 322 is a test valve 324 that is used to selectively allow and prevent fluids from entering the interior of tubular string 304 from the exterior of tubular string 304.

Formation fluid evaluation system 300 includes an upper packer 326 positioned uphole of the uppermost zone 306. Positioned uphole of upper packer 326 is fluid unloading assembly 328 that is depicted as a hydraulic pump wherein power fluid within hydraulic line 330 circulated downhole to drive a motor within fluid unloading assembly 328 such that fluid 334 from isolated zone 308 is drawn into tubular string 304 through test valve 324 and up to the surface. In embodiments using fluid unloading assembly 328 those skilled in the art will recognize that upper packer 326 may be optionally removed as loss of power fluid into zones above the isolated zones is not a concern. In such case, fluid unloading assembly 328 may be located proximate packer 220. Fluid unloading assembly 328 also includes a nipple and a seal bore that allow the passage of formation evaluation instrument 336 carried by conveyance 338 therethrough and is sealed by a plug also carried by conveyance 338. In this configuration, fluid 334 can be pumped uphole to unload zone 308 until reservoir fluid is produced. The characteristics of the fluid produced from zone 308 can then be evaluated by formation evaluation instrument 336 or other systems associate with formation evaluation instrument 336. If the characteristic of the reservoir fluid 334 received from isolated zone 308 matches a predetermined characteristic, such as a sufficient oil show, then formation fluid evaluation system 300 is designed to treat isolated zone 308. Specifically, formation fluid evaluation system 300 includes a treatment valve 340 that is used to inject a treatment fluid, such as a fracture fluid with or without propping agents into zone 308. In one implementation, this is achieved by removing formation evaluation instrument 336 and pumping the treatment fluid down tubular string 318. Following the treatment process, formation evaluation instrument 336 can be redeployed and fluid from zone 308 may be reevaluated in a manner similar to that described above wherein it may be required that fracture fluids are unloaded from zone 308 prior to production of reservoir fluids for evaluation.

Due to the unique configuration of formation fluid evaluation system 300, each of the multiple zones 306, 308, 310 can be evaluated and treated in this manner by merely repositioning formation fluid evaluation system 300 in wellbore 302 adjacent a respective one of the zones and isolating that zone, providing a seal uphole of the uppermost zone, unloading fluid from the isolated zone, receiving reservoir fluid from the isolated zone into the interior of the tubular string, determining a characteristic of the reservoir fluid received from the isolated zone and treating the zone if desired.

Referring next to FIG. 4, therein is representatively illustrated a formation fluid evaluation system that is generally designated 400 and which embodies principles of the present invention. Formation fluid evaluation system 400 is disposed within a wellbore 402 that includes casing 404. Wellbore 402 traverses various earth strata including a plurality of zones of interest such as zones 406, 408, 410. As illustrated, casing 404 includes perforation 412, 414, 416 that correspond in location with zones 406, 408, 410, respectively.

Formation fluid evaluation system 400 is interconnected within a tubular string 418. At its lower end, formation fluid evaluation system 400 includes isolation packer 420 and isolation packer 422 that operate as a pair of straddle packers to isolate the zone of interest to be tested. Disposed between packers 420, 422 is a test valve 424 that is used to selectively allow and prevent fluids from entering the interior of tubular string 404 from the exterior of tubular string 404.

Formation fluid evaluation system 400 includes an upper packer 426 positioned uphole of the uppermost zone 406. Positioned uphole of upper packer 426 is fluid unloading assembly 428 that is depicted as an electrical submersible pump that receives power via conductor 430 which drives fluid unloading assembly 428 such that fluid 434 from isolated zone 408 is drawn into tubular string 404 through test valve 424 and up to the surface. As illustrated, conductor 430 is positioned external to tubular string 418 and may be included as part of a cable assembly which includes multiple conductors. In addition to providing power to fluid unloading assembly 428, conductor 340 may be used to monitor the pump performance, measure pressure differential across the pump and the like.

Also powered by conductor 430 is a formation evaluation instrument 436 that is interconnected with tubular string 418. In addition to providing power to formation evaluation instrument 436, conductor 430 may transmit data, command signals and the like between formation evaluation instrument 436 and the surface. In embodiments where conductor 430 only provides power, data and command signals may alternatively be transmitted between formation evaluation instrument 436 and the surface by wireless telemetry, such as acoustic, pressure pulse, electromagnetic telemetry and the like. In operation, fluid 434 is pumped uphole to unload zone 408 until reservoir fluid is produced. The characteristics of the fluid produced from zone 408 can then be evaluated by formation evaluation instrument 436 or other systems associate with formation evaluation instrument 436.

Due to the unique configuration of formation fluid evaluation system 400, each of the multiple zones 406, 408, 410 can be evaluated in this manner by merely repositioning formation fluid evaluation system 400 in wellbore 402 adjacent a respective one of the zones and isolating that zone, providing a seal uphole of the uppermost zone, unloading fluid from the isolated zone, receiving reservoir fluid from the isolated zone into the interior of the tubular string and determining a characteristic of the reservoir fluid received from the isolated zone.

Referring next to FIGS. 5A-5B, therein is representatively illustrated a formation fluid evaluation system that is generally designated 500 and which embodies principles of the present invention. Unlike the previously described formation fluid evaluation systems, formation fluid evaluation system 500 may be disposed in a wellbore that has not previously been perforated. As best seen in FIG. 5A, formation fluid evaluation system 500 is being deployed within wellbore 502 that includes casing 504. Wellbore 502 traverses various earth strata including a plurality of zones of interest such as zones 506, 508, 510. As illustrated, casing 504 includes perforation 514, 516 that correspond in location with zones 508, 510, respectively. Also as illustrated, the casing adjacent to zone 506 has not been perforated. Preferably, formation fluid evaluation system 500 is used to perforate and evaluate the lowermost zone, depicted as zone 510, then progresses uphole, zone by zone, until all zones of interest have been perforated and tested. Accordingly, FIG. 5A depicts a scenario in which zone 510 has been perforated and evaluated, zone 508 has been perforated but not yet evaluated and zone 506 has not been perforated or evaluated.

Formation fluid evaluation system 500 is interconnected within a tubular string 518. At its lower end, formation fluid evaluation system 500 includes a string of tubing conveyed perforating guns 540 that are used to form perforations in casing 504 such as perforations 514 adjacent to zone 508. In the illustrated embodiment, perforating guns 540 employ a select fire system that allows only one or some of the guns to be fired at one time. As such, a plurality of zones can be sequentially perforated and evaluated in a single trip using formation fluid evaluation system 500 by aligning the perforating guns with a zone of interest, perforating the zone, repositioning the system for isolation and testing of the zone then repeating the process for the other zones of interest.

As best seen in FIG. 5B, formation fluid evaluation system 500 includes isolation packer 520 and isolation packer 522 that operate as a pair of straddle packers to isolate the zone of interest to be tested. Disposed between packers 520, 522 is a test valve 524 that is used to selectively allow and prevent fluids from entering the interior of tubular string 504 from the exterior of tubular string 504. Positioned uphole of packer 520 is fluid unloading assembly 528 that is depicted as a fluid operated pump wherein power fluid 530 circulated through annulus 532 drives fluid unloading assembly 528 such that fluid 534 from isolated zone 508 is drawn into tubular string 504 through test valve 524 and up to the surface. Fluid unloading assembly 528 also includes a nipple and a seal bore that allow the passage of formation evaluation instrument 536 carried by conveyance 538 therethrough and is sealed by a plug also carried by conveyance 538. In this configuration, fluid 534 can be pumped uphole to unload zone 508 until reservoir fluid is produced. The characteristics of the fluid produced from zone 508 can then be evaluated by formation evaluation instrument 536 or other systems associate with formation evaluation instrument 536.

Due to the unique configuration of formation fluid evaluation system 500, each of the multiple zones 506, 508, 510 can be perforated and evaluated in this manner by merely repositioning formation fluid evaluation system 500 in wellbore 502 adjacent a respective one of the zones and perforating the casing, isolating the zone, unloading fluid from the isolated zone, receiving reservoir fluid from the isolated zone into the interior of the tubular string and determining a characteristic of the reservoir fluid received from the isolated zone.

In certain instances, it may be desirable to use tubing conveyed perforating guns 540 in association with one of the previously discussed formation fluid evaluation systems such as systems 100, 200, 300, 400. For example, if it is desired to perforate numerous zones prior to evaluating such zones, it would be desirable to use a formation fluid evaluation system incorporating an upper packer that operable to be set uphole of the uppermost perforated zone to prevent any of the power fluid that drives the fluid unloading assembly from entering perforated zones above the zone being evaluated. Likewise, it may be desirable to sequentially perforate, evaluate, stimulate and reevaluate zones of interest by incorporating the tubing conveyed perforating guns 540 into system 300 discussed above.

Referring next to FIGS. 6A-6B, therein is representatively illustrated a formation fluid evaluation system that is generally designated 600 and which embodies principles of the present invention. As best seen in FIG. 6A, formation fluid evaluation system 600 is being deployed within wellbore 602 that includes casing 604. Wellbore 602 traverses various earth strata including a plurality of zones of interest such as zones 606, 608, 610. As illustrated, casing 604 includes perforation 614, 616 that correspond in location with zones 608, 610, respectively. Also as illustrated, the casing adjacent to zone 606 has not been perforated. FIG. 6A depicts a scenario in which zone 610 has been perforated and evaluated, zone 608 has been perforated but not yet evaluated and zone 606 has not been perforated or evaluated.

Formation fluid evaluation system 600 is interconnected within a tubular string 618. At its lower end, formation fluid evaluation system 600 includes a valve that selectively allows the passage of wireline conveyed perforating guns 640 therethrough that are used to form perforations in casing 604 such as perforations 614 adjacent to zone 608. In the illustrated embodiment, a plurality of zones can be sequentially perforated and evaluated in a single trip using formation fluid evaluation system 600 by deploying the perforating guns through tubular string 618, perforating the zone, retrieving the perforating guns, repositioning the system for isolation and testing of the zone then repeating the process for the other zones of interest.

As best seen in FIG. 6B, formation fluid evaluation system 600 includes isolation packer 620 and isolation packer 622 that operate as a pair of straddle packers to isolate the zone of interest to be tested. Disposed between packers 620, 622 is a test valve 624 that is used to selectively allow and prevent fluids from entering the interior of tubular string 604 from the exterior of tubular string 604. Positioned uphole of packer 620 is fluid unloading assembly 628 that is depicted as a fluid operated pump wherein power fluid 630 circulated through annulus 632 drives fluid unloading assembly 628 such that fluid 634 from isolated zone 608 is drawn into tubular string 604 through test valve 624 and up to the surface. Fluid unloading assembly 628 also includes a nipple and a seal bore that allow the passage of formation evaluation instrument 636 carried by conveyance 638 (as well as wireline conveyed perforating guns 640) therethrough and is sealed by a plug also carried by conveyance 638. In this configuration, fluid 634 can be pumped uphole to unload zone 608 until reservoir fluid is produced. The characteristics of the fluid produced from zone 608 can then be evaluated by formation evaluation instrument 636 or other systems associate with formation evaluation instrument 636.

Due to the unique configuration of formation fluid evaluation system 600, each of the multiple zones 606, 608, 610 can be perforated and evaluated in this manner by merely repositioning formation fluid evaluation system 600 in wellbore 602 adjacent a respective one of the zones and perforating the casing, isolating the zone, unloading fluid from the isolated zone, receiving reservoir fluid from the isolated zone into the interior of the tubular string and determining a characteristic of the reservoir fluid received from the isolated zone. It should be noted that formation fluid evaluation systems 100, 200, 300, 400 discussed above could be configured to utilize wireline conveyed perforating guns 640 in order to enable sequential perforate and evaluate operations as well as perforate, evaluate, stimulate and reevaluate operations.

Referring next to FIGS. 7A-7B, therein is representatively illustrated a formation fluid evaluation system that is generally designated 700 and which embodies principles of the present invention. As best seen in FIG. 7A, formation fluid evaluation system 700 is being deployed within wellbore 702 that includes casing 704. Wellbore 702 traverses various earth strata including a plurality of zones of interest such as zones 706, 708, 710. As illustrated, casing 704 includes perforation 714, 716 that correspond in location with zones 708, 710, respectively. Also as illustrated, the casing adjacent to zone 706 has not been perforated. FIG. 7A depicts a scenario in which zone 710 has been perforated and evaluated, zone 708 has been perforated but not yet evaluated and zone 706 has not been perforated or evaluated.

Formation fluid evaluation system 700 is interconnected within a tubular string 718. At its lower end, formation fluid evaluation system 700 includes isolation packer 720 and isolation packer 722 that operate as a pair of straddle packers to isolate the zone of interest to be perforated and tested. Disposed between packers 720, 722 is a ported sub 740 that may be operated as a hydro-jet perforating gun used to form perforations in casing 704 such as perforations 714 adjacent to zone 708. In the illustrated embodiment, a plurality of zones can be sequentially perforated and evaluated in a single trip using formation fluid evaluation system 700 by deploying the system to a zone of interest, isolating the zone, perforating the zone, testing of the zone then repeating the process for the other zones of interest.

Also disposed between packers 720, 722 is a test valve 724 that is used to selectively allow and prevent fluids from entering the interior of tubular string 704 from the exterior of tubular string 704. Positioned uphole of packer 720 is fluid unloading assembly 728 that is depicted as a fluid operated pump wherein power fluid 730 circulated through annulus 732 drives fluid unloading assembly 728 such that fluid 734 from isolated zone 708 is drawn into tubular string 704 through test valve 724 and up to the surface. Fluid unloading assembly 728 also includes a nipple and a seal bore that allow the passage of formation evaluation instrument 736 carried by conveyance 738 therethrough and is sealed by a plug also carried by conveyance 738. In this configuration, fluid 734 can be pumped uphole to unload zone 708 until reservoir fluid is produced. The characteristics of the fluid produced from zone 708 can then be evaluated by formation evaluation instrument 736 or other systems associate with formation evaluation instrument 736.

Due to the unique configuration of formation fluid evaluation system 700, each of the multiple zones 706, 708, 710 can be perforated and evaluated in this manner by merely repositioning formation fluid evaluation system 700 in wellbore 702 adjacent a respective one of the zones and perforating the casing, isolating the zone, unloading fluid from the isolated zone, receiving reservoir fluid from the isolated zone into the interior of the tubular string and determining a characteristic of the reservoir fluid received from the isolated zone. It should be noted that formation fluid evaluation systems 100, 200, 300, 400 discussed above could be configured to utilize hydro-jet perforating gun 740 in order to enable sequential perforate and evaluate operations as well as perforate, evaluate, stimulate and reevaluate operations.

While this invention has been described with a reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments. 

1. A formation fluid evaluation system interconnected within a tubular string for operation in a wellbore having multiple zones, the evaluation system comprising: a pair of straddle packers that isolates one zone of the multiple zones; a test valve disposed between the straddle packers, the test valve receiving fluid from the isolated zone into the interior of the tubular string; an upper packer positioned uphole of an uppermost zone of the multiple zones; a fluid unloading assembly position uphole of the upper packer, the fluid unloading assembly operable to draw fluid from the isolated zone into the tubular string through the test valve; and a formation evaluation instrument disposed within the tubular string that determines a characteristic of the fluid received from the isolated zone, wherein the evaluation system is operable to sequentially isolate individual zones of the multiple zones and evaluate fluid received from the individual zones in a single trip.
 2. The system as recited in claim 1 wherein the test valve further comprises a screen element.
 3. The system as recited in claim 1 wherein the fluid unloading assembly further comprises a pump.
 4. The system as recited in claim 3 wherein the pump is selected from a jet pump, a progressive cavity pump, a hydraulic driven piston pump, an electrical submersible pump and a syringe pump.
 5. The system as recited in claim 1 wherein the fluid unloading assembly further comprises a gas lift valve.
 6. The system as recited in claim 1 wherein the formation evaluation instrument is run in the tubular string on a conveyance and passes through the fluid unloading assembly.
 7. The system as recited in claim 1 wherein the formation evaluation instrument further comprises at least one sensor coupled to the tubular string.
 8. The system as recited in claim 1 wherein data obtained by the formation evaluation instrument relative to the characteristic of the fluid is transmitted to the surface via a conductor operably associated with the formation evaluation instrument.
 9. The system as recited in claim 1 wherein data obtained by the formation evaluation instrument relative to the characteristic of the fluid is transmitted to the surface via a wireless telemetry device operably associated with the formation evaluation instrument.
 10. The system as recited in claim 1 wherein the characteristic of the fluid is at least one of temperature, pressure, flow rate and fluid composition.
 11. The system as recited in claim 1 further comprises a treatment valve disposed between the straddle packers, the treatment valve operable to inject fluid from the tubular string into the isolated zone.
 12. A method of evaluating multiple zones during a single trip into a wellbore, the method comprising: interconnecting a formation fluid evaluation assembly within a tubular string; disposing the formation fluid evaluation assembly in the wellbore proximate one zone of the multiple zones and isolating the zone; providing a seal uphole of an uppermost zone of the multiple zones; unloading fluid from the isolated zone into the tubular string; receiving reservoir fluid from the isolated zone into the interior of the tubular string; determining a characteristic of the reservoir fluid received from the isolated zone; and performing the disposing, isolating, providing, unloading, receiving and determining steps for each of the multiple zones in a single trip.
 13. The method as recited in claim 12 further comprising the step of filtering the fluid entering the tubular string from the isolated zone.
 14. The method as recited in claim 12 wherein the step of unloading fluid from the isolated zone into the tubular string further comprises pumping the fluid to the surface.
 15. The method as recited in claim 12 wherein the step of unloading fluid from the isolated zone into the tubular string further comprises lifting the fluid to the surface.
 16. The method as recited in claim 12 wherein the step of determining a characteristic of the reservoir fluid received from the isolated zone further comprises obtained data relative to the characteristic of the fluid and transmitting the data to the surface via a conductor.
 17. The method as recited in claim 12 wherein the step of determining a characteristic of the reservoir fluid received from the isolated zone further comprises obtained data relative to the characteristic of the fluid and transmitting the data to the surface via wireless telemetry.
 18. The method as recited in claim 12 wherein the step of determining a characteristic of the reservoir fluid received from the isolated zone further comprises determining at least one of temperature, pressure, flow rate and fluid composition.
 19. The method as recited in claim 12 further comprising the step of performing a treatment operation on the isolated zone if the characteristic of the reservoir fluid received from the isolated zone matches a predetermined characteristic.
 20. A method of evaluating multiple zones during a single trip into a wellbore, the method comprising: interconnecting a formation fluid evaluation assembly within a tubular string; disposing the formation fluid evaluation assembly in the wellbore proximate one zone of the multiple zones and isolating the zone; providing a seal uphole of an uppermost zone of the multiple zones; unloading fluid from the isolated zone into the tubular string; receiving reservoir fluid from the isolated zone into the interior of the tubular string; determining a characteristic of the reservoir fluid received from the isolated zone; if the characteristic of the reservoir fluid received from the isolated zone matches a predetermined characteristic, then treating the isolated zone and repeating the receiving and determining step; and performing the disposing, isolating, providing, unloading, receiving, determining and conditional treating steps for each of the multiple zones in a single trip. 